1. Field of the Invention
The present invention relates to a heat exchanger, and more particularly to a fluid heat exchanger. More specifically, the present invention relates to a fluid heat exchanger for rapidly heating a fluid passing between two tubes of the heat exchanger.
2. Known Art
Typically, fluid heating systems are comprised of a metal resistive coil, referred to as a heating element, which winds around the outside of a hollow tube. A fluid flows through the tube and is heated by the heating element; however, this construction has several drawbacks. Prior art heating systems do not efficiently heat the fluid, especially at low fluid flow rates. Further, such heating systems are not easily formed into a compact shape and require an excessive period of time to heat the fluid to a desired temperature for use in fluid heating system.
An advance in the art is found in U.S. Pat. No. 5,590,240 to Rezabek which discloses a fluid heating system that includes an insulated housing containing longitudinally proceeding high efficiency tubular heat exchangers. These tubular heat exchangers have inner and outer helical passageways and a return passageway proceeding along a longitudinal axis through the helical passageways which are in fluid communication with each other. A heat transfer fluid, such as ultra pure water, sequentially passes through each of the helical passageways before passing through the return passageway. The inner helical passageway has resistance coils intermittently wrapped about its periphery for heating the heat transfer fluid. However, the Rezabek heating system requires the heat transfer fluid to travel the length of the housing at least three times to achieve greater fluid heating efficiency. In addition, due to the amount of required spacing between the tubing, the Rezabek system lacks a compact construction, nor is the Rezabek system easy to manufacture. Therefore, there appears a need in the art for a fluid heating system that is compact in construction, easy to manufacture, and rapidly brings the fluid temperature to a desired temperature level in an efficient manner.